1. Field of the Invention
The present invention relates to the production of propylene oxide by a process wherein propane is dehydrogenated and the product mixture comprised of propylene, propane and hydrogen from the dehydrogenation, together with added oxygen, is reacted to form propylene oxide.
2. Description of the Prior Art
Integrated processes have been proposed wherein propane is dehydrogenated to form propylene with the propylene being epoxidized, using a hydroperoxide or hydrogen peroxide, to form propylene oxide. See, for example, U.S. Pat. No. 5,599,956. Such prior procedures have required the costly separation of propylene from hydrogen in the dehydrogenation product prior to the epoxidation of the propylene to propylene oxide.
In addition, methods have been proposed such as suggested in U.S. Pat. Nos. 4,990,632 and 5,008,412 wherein propane is dehydrogenated and the resultant propylene is oxidized to propylene oxide using a catalyst such as silver oxide; oxygen is eliminated by oxidation from the recycle stream.
Further, in EP 0850936 a process is described wherein propane is dehydrogenated, oxygen is added to the dehydrogenation product and the resulting mixture is epoxidized over a gold catalyst with oxygen being eliminated from the recycle stream.
The instant invention represents a significant improvement over prior procedures in that the mixture of propylene, propane, and hydrogen from the propane dehydrogenation is used, without separation of the components, to form propylene oxide over a Pd/TS-1 catalyst with recycle of oxygen to the epoxidation.